Abstract

In an ideal setting, the target area could be located directly using a non-invasive, high resolution, high speed tracking or imaging modality. Currently, however, there is no single device capable of meeting all these demands. Options available are either invasive, like biplanar fluoroscopy [34-38] or EM tracking [2, 20, 41], are still under development, like US tracking [13, 29, 42], live Magnetic Resonance Imaging (MRI) [17, 21, 26, 27] or monoscopic fluoroscopy [3, 4], or require correlation between external signals and sparsely recorded internal data [23, 25, 32, 33]. Since most of these technologies are not yet available clinically (like live MRI, US tracking, or monoscopic fluoroscopy), cannot be used universally (like EMtracking) or are too invasive (like real-time biplanar fluoroscopy), the main focus is placed on hybrid methods which require external surrogates to fill the gaps between less frequently acquired internal data.